GENETIC DISSECTION OF HERBICIDE TOLERANCE IN MAIZE BY MOLECULAR MARKERS

Ln order to detect the genetic architecture of maize tolerance to Alac hlor, a widely used chloroacetanilide, linkage analysis between the ex pression of the trait and allelic composition of molecular markers was performed. The experiment was carried out on a population of 142 reco mbinant inbred lines, developed starting from the F-1 between two line s with different reactivity to the herbicide, and self-fertilized for 10 generations; the lines were typed by 48 RFLP markers and 66 microsa tellites (SSR). Besides seedling tolerance, evaluated as proportion of normal (non-injured) plants after herbicide treatment, other minor co mponents of tolerance were studied: seed germination ability, pollen g ermination and tube growth in the presence of the herbicide. The analy sis, performed by three statistical methods, revealed the presence of factors controlling seedling tolerance on seven chromosomal regions. F ive QTLs appeared to be involved in seed germination ability in the pr esence of Alachlor, four QTLs in pollen tolerance in terms of germinat ion and four in tube growth under stress were detected. Three loci, on chromosomes 1, 7 and 10, explained most of the variation of seedling tolerance, thus being interesting candidate for marker-assisted select ion.